Environmental management is a primary mission of the U.S. Army Corps of Engineers (USACE). Accounting for the natural environment around us is a key component of San Francisco District’s (SPN) strategic objectives, and we continue to promote engineering with nature for long-term sustainability and benefits, and resilience of project solutions.
What we refer to as engineering with nature (EWN) is the “intentional alignment of natural and engineering processes to deliver economic, environmental and social benefits efficiently and sustainably through collaboration. By combining science and engineering, USACE has been able to produce operational efficiencies that are actively reducing demands on finite resources, minimizing the ecological footprint of projects and enhancing the quality of project benefits.” Or, more simply put, the district is learning to work with nature to better define its projects, save money, and have long-term benefits.
San Francisco is one of six proving ground districts in USACE that applies EWN, along with the Mobile, St. Louis, Galveston, Buffalo, and Philadelphia districts. Of these, SPN is the only one operating on the West Coast.
The U.S. Army Engineer Research and Development Center defines an EWN proving ground as a “district committed to broad integration of EWN principles and practices into all business lines. Proving grounds are places where innovative ideas are tested on the ground, throughout USACE processes, and through new research and innovation. Districts [that] become proving grounds will document processes, milestones, and lessons learned in the implementation of EWN measures so others can learn from their experience.”
Restoring Dry Creek’s habitat in Sonoma, California, is an ongoing SPN project that is an example of how successful EWN can be when organizations build on first understanding, then deliberately work with nature to accomplish its goals.
The overall effort entails repairing and enhancing 6 miles of Dry Creek habitat to improve living conditions for local endangered coho salmon, a keystone species, and the threatened steelhead trout. Dry Creek’s cool, clear water is perfect for salmon and steelhead, but juvenile fish cannot survive because the water runs too quickly, and the territory is rapidly changing. Young coho salmon and steelhead trout now have proper shelter and hiding places in Dry Creek thanks to Sonoma Water, USACE, and McCullough Construction, Inc.
USACE and its partners are combating this issue by constructing alcoves, riffles (i.e., small rapids that increase the ratio of dissolved oxygen in the water), backwaters, and side channels that slow the flow of water and provide a safe haven for young fish. Natural resources like logs and rocks are used to create the side channels to give fish places to escape high flows. Bank stabilization lessens excessive erosion, while anchored boulders produce riffles, and secured log jams provide refuge and slow the water. The reintroduction of native flora around the creek is also used for erosion control and shade.
One of the team’s long-term biologists, Ellie Covington, reported that there is distinct evidence of tracked salmon and trout returning to restored areas of Dry Creek to spawn and raise juvenile fish ever since the new features were constructed. This finding would not have been possible without base line designs that unite science and engineering to establish stable plans to enhance the creek’s ecology.
“When it comes to integrating engineering with nature into our district’s projects, we must remember where we are and the massive geographic space we work in to assist the natural environment while being considerate of the adjacent communities,” Covington said. “We prioritize bettering habitats and the surrounding area, and when we see success, it provides momentum to stay motivated because even seemingly small projects can be daunting but are equally meaningful.”
Back in 2014, the local community and the district saw the completion of the first mile of Dry Creek rehabilitation, which included logs, boulders, and hundreds of native plants. By the end of the project, the 14-mile-long creek will have 6 miles of habitat rebuilt into it.
“Our leadership here at SPN is continually supportive of our environmental research and restoration, and I believe that is a large reason as to why we maintain the rank as one of the top proving grounds within the USACE,” Covington noted.